This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 4 |
| 3 | 20 |
| 4 | 127 |
| 5 | 967 |
| 6 | 8549 |
| 7 | 85829 |
| 8 | 962308 |
| 9 | 11895252 |
| 10 | 160475855 |
| 11 | 2343491207 |
| 12 | 36795832297 |
| 13 | 617662302441 |
| 14 | 11031160457672 |
| 15 | 208736299803440 |
| 16 | 4169680371133507 |
| 17 | 87648971646028515 |
| 18 | 1933298000313801349 |
| 19 | 44633323736412392093 |
| 20 | 1076069422794010119112 |